In an electronic component in which two substrates at least one of which is transparent have an organic element or an organic material therebetween, the following measures are taken to protect the organic element or organic material from moisture, water and others: for example, respective outer circumferential portions of the two substrates are bonded to each other through a sealing material of a resin; and further a drying agent is located inside the electronic component. However, the bonding through the resin is insufficient in a gas barrier performance (an air-tightness), so that water molecules gradually invade the inside. Thus, the bonding through the resin does not give a sufficient reliability.
In the meantime, in the case of a sealing material containing a low-melting glass and filler particles for making the thermal expansion coefficient of the sealing material consistent with that of the substrates, the substrates can be bonded to each other with the high gas barrier performance (the high air-tightness). However, this sealing material needs to be made remarkably higher in bonding temperature than the resin sealing material to cause a problem that the resultant thermal environment exceeds the heat resistance of the organic element or organic material located inside the electronic component.
A means or method invented as a result thereof is a laser sealing which can attain a local heating. The laser sealing makes use of a sealing material containing a low-melting glass capable of attaining airtight bonding, and low-expandable filler particles. This low-melting glass needs to have a property of absorbing a laser ray radiated across a transparent substrate to be raised in temperature, thereby softening and flowing. This method makes it possible to heat only respective outer circumferential portions of two substrates at least one of which is transparent. Thus, a glass bonding high in the gas barrier performance (the air-tightness) can be attained without giving any thermal damage to the organic element or organic material located inside the electronic component.
In a display or some other in which an organic light emitting diode (OLED), a glass substrate having in its outer circumferential portion a pre-fired sealing material is put onto a glass substrate on which another OLED and interconnections are formed, and then a laser is radiated across one of the glass substrates onto the sealing material, thereby causing the low-melting glass in the sealing material to soften and flow. In this way, the two glass substrates are bonded to each other.
Patent Literature 1 discloses an organic light emitting diode display using an airtight seal, in which a material used for the airtight seal is a frit containing a predetermined glass and a lithium aluminosilicate filler, the lithium aluminosilicate filler making the frit low in a thermal expansion coefficient, and in which the material is heated through a laser to be meltable. This frit contains a V—P—Sb—O based low-melting glass heatable through a laser, and a filler LiAlSiO4 (β-eucryptite) for making the thermal expansion coefficient of the frit consistent with that of a glass substrate.
Patent Literature 2 discloses a technique of using the same frit as disclosed in Patent Literature 1 and further sintering the frit preliminarily in a nitrogen atmosphere to prevent the immersion endurance from being lowered.